There are many existing methods of displaying information on an animated map. In animated map technology, a “slippymap” is a tile-based map that permits a user to perform pan and zoom display controls. The user interface that controls a slippymap is known as a slippymap frame, in which data may be displayed in one or more rasterized layers, which are layers that overlay raster imagery onto the slippymap. Each raster layer is a grid of pixels that adds content to the map, such as precipitation and other weather patterns, or traffic capacity or speed. A slippymap may also include a base layer, which is the first map layer loaded into the slippymap frame. This base layer is not transparent, whereas other layers have partly or fully transparent parts so that the base layer shows through. The base layer may also be a raster layer. Other data may be present in one or more vector layers, which are layers that represent data with discretely-described objects rather than a grid of pixels.
Raster layers are not interactive, but vector layers may be, since client-side code draws and understands vector layers. Animated raster layers are layers of raster imagery where the pixel data is replaced on a timer to animate content. This may display changing conditions over time, such as for air temperature, pavement conditions, or traffic speeds. Vector layers may also be animated.
In existing technology, when users wish to zoom in or zoom out on an animated map, old images are discarded and new ones are loaded each and every time the user activates a zoom in or zoom out command. Each such command request loads a new image that has the same resolution as the client's screen's view of the map. The state of the prior art therefore involves simply loading data tiles from the server for every time-slice selected, resulting in long data transfer times since an animated raster overlay is many times larger than a static raster overlay—and like a static raster overlay, it has to be reloaded every time the user changes the zoom level.
Existing systems and methods that attempt to reduce the volume of data downloaded include techniques such as limited animation, which is a type of flash animation which reuses common parts between frames. In this type of animation, an image is created with fewer attributes to create the same effect so that the overall number of images is reduced, resulting in a lower cost. However, these techniques do not lend itself well to accuracy in the display of raster imagery such as weather data in slippymap technology, since the image selected for zooming in or out must still be separately downloaded when selected.
These existing methods of displaying animated data when a user zooms in or out are therefore cumbersome due to lengthy download times resulting from high bandwidth consumption, and they are costly to implement for the same reason.